This longitudinal study examines the little researched, yet extremely important, transition from high school to young adulthood among late adolescents (17-21 years of age) with type 1 diabetes. These adolescents are in a challenging time when their glycemic control, diabetes management, and quality of life may be relatively worse, their peers are involved in alcohol use and weight control behaviors, and they need to be assuming responsibility for their diabetes. Thus, we will be focusing on outcome variables of glycemic control, quality of life, diabetes management, alcohol use, weight control behaviors, and assumption of responsibility for diabetes. Building upon research from younger adolescents, we will also examine personal and environmental factors influencing glycemic control, diabetes-related quality of life, diabetes management, and responsibility for diabetes within two major situational transitions: education and living situation. To capture this transition from high school to young adulthood, we will follow key variables among 150 late adolescents for approximately 18 months, from the last 3 months in high school through the first year post-high school. Multi-level regression modeling will be used to examine both changes over time in outcome, personal, and environmental factors as well as how changes overtime in the outcomes are related to environmental and personal characteristics in the context of situational transitions. Identifying these key times and influential factors will provide information critical to designing future effective interventions to improve glycemic control and quality of life for these adolescents as they transition to adulthood. In addition, this study addresses two objectives of the Program Announcement PA-03-159: Chronic Illness Self-Management in Children. First, it addresses the objective that focuses on examining factors that promote the transfer of self-management responsibility, including the stage of development. This study also addresses a second objective, examining factors to sustain self-management and integration of it within the home, school, and community.